Recently, the biological molecular process detection has attracted more and more attention, for example, cell activity detection, DNA detection, bioprotein detection, drug screening and so on. Compared with the optical detection, the direct electrical activity detection is simple in operation and convenient for in-vivo detection. At present, the direct electrical activity detection mainly uses two conventional solid-state biosensors, i.e., a microelectrode array and a field effect device. However, in the two conventional sensors, an additional reference electrode is needed for setting a difference in voltage between a solution and a substrate of the sensor. As a result, it is difficult to realize large-scale integration in a standard integrated circuit process of conventional sensors, and the further reduction in cost and development in portability of such sensors are hindered.
As a common basic unit in a semiconductor device, a floating gate transistor has two ports, i.e., a floating gate and a control gate, which both may be used as an input terminal. Meanwhile, the control of the turn-on voltage and the saturation current may be realized by a superposition principle of the control gate and the floating gate. Therefore, some scholars have proposed devices structurally similar to floating gate transistors. The use of the control gate makes up the deficiency that the conventional sensors require additional reference electrodes. However, the control gate can only be used to set a quiescent operating point. During the actual detection, there are electrochemical noise caused by the ionic movement of an electrolyte solution, slow DC drift caused by the change in temperature, and so on. The noise will inhibit or hinder accurate signal detection, so it is necessary to provide a novel sensor to overcome this noise, make up the deficiencies of the existing sensors and realize high signal-to-noise ratio detection.